U.S. patent application number 10/173379 was filed with the patent office on 2003-12-18 for interactive rock stability display.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Cook, John Mervyn.
Application Number | 20030233194 10/173379 |
Document ID | / |
Family ID | 22631736 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030233194 |
Kind Code |
A1 |
Cook, John Mervyn |
December 18, 2003 |
Interactive rock stability display
Abstract
A method and system is disclosed for interactively displaying
estimated stability of rock surrounding a wellbore. The display
shows a three-dimensional representation of the orientation of a
portion of the wellbore and the associated estimation of stability
of the rock surrounding the wellbore. The user can alter the
orientation of the portion of the wellbore, after which in real
time the stability estimation is recalculated and redisplayed. The
method and system can be used for planning or modifying a well
plan, either before or during the drilling process. The method and
system can also be used for diagnosis of stability problems. The
method and system can also be used for displaying and analyzing the
estimated stability of perforations surrounding a wellbore and for
planning and arranging such perforations.
Inventors: |
Cook, John Mervyn;
(Cambridge, GB) |
Correspondence
Address: |
Intellectual Property Law Department
Schlumberger-Doll Research
36 Old Quarry Road
Ridgefield
CT
06877-4108
US
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Ridgefield
CT
|
Family ID: |
22631736 |
Appl. No.: |
10/173379 |
Filed: |
June 17, 2002 |
Current U.S.
Class: |
702/16 |
Current CPC
Class: |
E21B 49/006 20130101;
G01V 1/34 20130101 |
Class at
Publication: |
702/16 |
International
Class: |
G01V 001/28 |
Claims
What is claimed is:
1. A system for interactively displaying estimated stability of
rock surrounding a wellbore comprising: a three-dimensional display
adapted to display to a user an orientation of a portion of the
wellbore and an estimation of stability of the rock surrounding the
portion of the wellbore; a user input system adapted to accept user
input representing changes in orientation of the portion of the
wellbore; and a processing system adapted to accept the user input
from the user input system and calculate and communicate to the
display a revised estimation of stability of the rock based on the
user input.
2. A system according to claim 1 wherein the processing system is
adapted to in real time calculate and communicate to the display
the revised estimate.
3. A system according to claim 2 wherein the processing system is
adapted to calculate and communicate to the display the revised
estimate in less than 2 seconds.
4. A system according to claim 3 wherein the processing system is
adapted to calculate and communicate to the display the revised
estimate in less than 0.2 seconds.
5. A system according to claim 1 the processing system is adapted
to calculate the revised estimation using other parameters relating
to rock properties in combination with the user input representing
changes in orientation of the portion of the wellbore.
6. A system according to claim 1 wherein the user input system is
further adapted to accept user input representing changes in fluid
pressure associated with the portion of the wellbore.
7. A system according to claim 6 wherein the fluid pressure is a
mud weight.
8. A system according to claim 1 further comprising a well plan for
specifying characteristics of a wellbore to be drilled, the well
plan incorporating information related to at least one orientation
displayed to the user with the three-dimensional display.
9. A system according to claim 8 wherein the well plan is stored on
a storage system of a second processing system, the at least one
orientation is an orientation selected by the user as being
preferred for the portion of the wellbore, and the well plan
comprises a trajectory that includes at least an approximation of
the selected orientation for a portion of the trajectory.
10. A system according to claim 1 wherein the estimation and
revised estimation are calculated by the processing system based on
parameters including one or more of the following: magnitudes of
three principal stresses in the vicinity of the portion of the
wellbore, orientation of the three principal stresses relative to
North; pore pressure of the rock, strength of the rock, friction
angle and Poisson's ratio, azimuth and deviation of the well, and
the fluid pressure in the portion of the wellbore.
11. A system according to claim 10 wherein the estimation and
revised estimation are calculated by the processing system based
further on parameters including one or more of the following:
plasticity of the rock, fluid flow rates in the rock, temperatures
of the rock, chemical and electrochemical properties of the rock,
and time since drilling of the portion of the wellbore.
12. A system according to claim 1 wherein the three-dimensional
display comprises a parallel projection display or a perspective
projection display.
13. A system according to claim 1 wherein the estimation of
stability is displayed to the user such that it indicated to the
user a prediction of likelihood of rock failure at different places
on the portion of the wellbore.
14. A system according to claim 13 wherein the three-dimensional
display displays the estimation of stability using different colors
to indicate the predicted likelihood of rock failure at different
places on the portion of the wellbore.
15. A system according to claim 1 wherein the orientation includes
both azimuth and inclination angle from vertical.
16. A system according to claim 1 wherein the three-dimensional
display is adapted to display a bedding plane of the rock.
17. A system according to claim 1 wherein the three-dimensional
display includes representations of the location of one or more
perforations relative to the portion of the wellbore and the
estimation of stability includes estimated stability of the rock
surrounding each of the one or more perforations.
18. A system according to claim 17 wherein the user input system is
further adapted to accept user input representing the addition,
deletion, and changes in location of the one or more
perforations.
19. A system according to claim 17 wherein the user input system is
further adapted to accept using input representing changes in
orientation of each of the one or more perforations with respect to
a central axis of the portion of the wellbore.
20. A system according to claim 1 wherein estimation of stability
and the revised estimation of stability are calculated by the
processing system using an elastic model.
21. A system according to claim 1 wherein estimation of stability
and the revised estimation of stability are calculated by the
processing system using an model incorporating placticity.
22. A system according to claim 5 wherein the other parameters are
assumed to be constant over the portion of the wellbore.
23. A system according to claim 1 wherein the portion of the
wellbore is less than 5 meters.
24. A method for interactively displaying estimated stability of
rock surrounding a wellbore comprising the steps of: displaying to
a user a three-dimensional representation of a first orientation of
a portion of the wellbore and a first estimation of stability of
the rock surrounding the portion of the wellbore associated with
the first orientation; receiving user input representing a second
orientation of the portion of the wellbore; calculating a second
estimation of stability of the rock associated with the second
orientation; and displaying to the user in real time a
three-dimensional representation of the second orientation of the
portion of the wellbore and the second estimation of stability of
the rock.
25. A method according to claim 24 wherein the processing system is
adapted to in real time calculate and communicate to the display
the revised estimate.
26. A method according to claim 24 wherein the step of calculating
the second estimation is performed in less than 2 seconds.
27. A method according to claim 26 wherein the step of calculating
the second estimation is performed in less than 0.2 seconds.
28. A method according to claim 24 the step of calculating the
second estimation uses other parameters relating to rock properties
in combination with the user input representing the second
orientation.
29. A method according to claim 24 further comprising the step of
receiving user input representing a fluid pressure associated with
the portion of the wellbore, and the step of calculating the second
estimation is based in part on the fluid pressure.
30. A method according to claim 29 further comprising the steps of:
selecting a preferred fluid pressure; and creating or modifying a
well plan specifying characteristics of a wellbore to be drilled,
the well plan incorporating the preferred fluid pressure.
31. A method according to claim 24 further comprising the steps of:
repeating the steps of receiving user input, calculating, and
displaying for further orientations; selecting a preferred
orientation; and creating or modifying a well plan specifying
characteristics of a wellbore to be drilled, the well plan
incorporating the preferred orientation.
32. A method according to claim 31 further comprising drilling at
least a portion of a well using the created or modified well
plan.
33. A method according to claim 24 wherein the first and second
estimations are calculated based on parameters including one or
more of the following: magnitudes of three principal stresses in
the vicinity of the portion of the wellbore, orientation of the
three principal stresses relative to North; pore pressure of the
rock, strength of the rock, friction angle and Poisson's ratio,
azimuth and deviation of the well, and the fluid pressure in the
portion of the wellbore.
34. A method according to claim 24 wherein the three-dimensional
representation comprises a parallel projection display or a
perspective projection display.
35. A method according to claim 24 wherein the first and second
estimations include predictions of likelihood of rock failure at
more than one place on the portion of the wellbore.
36. A method according to claim 24 wherein the steps of displaying
include displaying representations of the location of one or more
perforations relative to the portion of the wellbore and wherein
the first and second estimations of stability include estimated
stability of the rock surrounding each of the one or more
perforations.
37. A method according to claim 36 wherein the step of receiving
user input includes receiving user input representing the addition,
deletion, and changes in location of the one or more
perforations.
38. A method according to claim 24 wherein first and second
estimations of stability are calculated using an elastic model.
39. A method according to claim 28 wherein the other parameters are
assumed to be constant over the portion of the wellbore.
40. A method according to claim 24 wherein the portion of the
wellbore is less than 5 meters.
41. A method according to claim 24 further comprising the step of
comparing the at least the first or second estimation of stability
with data from an imaging tool, and wherein the method is carried
out after the start of drilling and before ending of drilling of
the wellbore.
42. A method according to claim 41 further comprising the steps of:
modifying a well plan based on a new orientation or mud weight; and
drilling portions of the wellbore according to the modified well
plan.
43. A method according to claim 29 wherein the method is carried
out after production of hydrocarbons has begun with the wellbore,
the fluid pressure is a drawdown pressure, and the method further
comprises the step of producing hydrocarbons at a selected drawdown
pressure that has been selected at least in part by the user
viewing the display of the second estimation.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of interactive
displays for use in oilfield services applications. In particular,
the invention relates to a three-dimensional interactive display
for rock stability applications relating to wellbore
construction.
BACKGROUND OF THE INVENTION
[0002] Wellbore instability and its associated drilling problems
are a major source of lost time and excess cost when drilling.
Planning for the management of instability is now becoming routine,
but communicating information on instability prediction, for
example to the diverse members of an asset or drilling team, can be
difficult. This is because many parameters enter into the
prediction, and displaying the influence of varying them all over
their potential ranges is not possible with conventional charts or
plots. There are also many outputs.
[0003] Three-dimensional displays for wellbore instability have
been used in a demonstration drilling simulator. See, IADC/SPE
59121, When Rock Mechanics Met Drilling: Effective Implementation
of Real-Time Wellbore Stability Control, I. D. R. Bradford, J. M.
Cook, E. F. M. Elewaut, J. A. Fuller, T. G. Kristiansen, and T. R.
Walsgrove (presented at the 2000 IADC/SPE Drilling Conference held
in New Orleans, La., Feb. 23-25, 2000); and SPE/IADC 67816, Meeting
Future Drilling Planning and Decision Support Requirements: A New
Drilling Simulator, H. -L. Balasch, J. Booth, I. D. R. Bradford, J.
M. Cook, J. D. Dowell, G. Ritchie, and I. Tuddenham (presented at
the SPE/IADC Drilling Conference held in Amsterdam, The
Netherlands, Feb. 27-Mar. 1, 2001). These displays were implemented
using a scientific programming language known as Matlab.
[0004] Colored polar plots have been used to display the results of
instability planning. For example polar colormap plots of the
severity of potential instability for wells at different
orientations have been implemented by Baker Hughes and Geomechanics
International. These techniques show the influences of changing the
well azimuth and deviation, with all other parameters fixed. The
color used at a particular point in the polar plot depends on how
much instability is predicted at the appropriate orientation.
However, techniques such as these are of limited use due in part to
the following:
[0005] 1. the person viewing must have an appreciation of how a
polar plot presents information; this is not a display method
familiar to many people outside geology and crystallography;
[0006] 2. the instability function must be integrated around the
circumference of the well, in order to generate a single value for
the colormap; this masks useful details of the circumferential
variation (e.g., its potential use in image log interpretation);
and
[0007] 3. the plots are relatively slow to generate, since they
have to cover a wide range of parameter space, but are then fixed;
any change in the earth parameters means a time-consuming
recalculation of the whole plot.
[0008] Finally, Three-dimensional displays have recently been used
successfully to convey instability information for a fixed
trajectory in a fixed earth model. However, these techniques
suffered in that they were not interactive with the user. This is
primarily because if the parameters of the trajectory or earth
model are changed, considerable recomputation is required to
display the new results, and there is no user-friendly method of
changing the trajectory of the wellbore.
SUMMARY OF THE INVENTION
[0009] Thus, it is an object of the present invention to provide a
system and method for interactively displaying rock stability
information to a user in three-dimensions.
[0010] According to the invention a system is provided for
interactively displaying estimated stability of rock surrounding a
wellbore comprising:
[0011] a three-dimensional display adapted to display to a user an
orientation of a portion of the wellbore and an estimation of
stability of the rock surrounding the portion of the wellbore;
[0012] a user input system adapted to accept user input
representing changes in orientation of the portion of the wellbore;
and
[0013] a processing system adapted to accept the user input from
the user input system and calculate and communicate to the display
a revised estimation of stability of the rock based on the user
input.
[0014] Also according to the invention, a method is provided for
interactively displaying estimated stability of rock surrounding a
wellbore comprising the steps of:
[0015] displaying to a user a three-dimensional representation of a
first orientation of a portion of the wellbore and a first
estimation of stability of the rock surrounding the portion of the
wellbore associated with the first orientation;
[0016] receiving user input representing a second orientation of
the portion of the wellbore;
[0017] calculating a second estimation of stability of the rock
associated with the second orientation; and
[0018] displaying to the user in real time a three-dimensional
representation of the second orientation of the portion of the
wellbore and the second estimation of stability of the rock.
BRIEF DESCRIPTION OF THE DRAWINGS:
[0019] FIG. 1 shows an interactive stability display according to a
preferred embodiment of the invention;
[0020] FIG. 2 shows features of the display screen, according to a
preferred embodiment of the invention;
[0021] FIG. 3 is a flow chart showing processing steps according to
the invention as implemented on a computer;
[0022] FIG. 4 is a flow chart showing steps of planning and
drilling a well according to a preferred embodiment of the
invention;
[0023] FIG. 5 is a diagram showing the implementation of an
interactive stability display used to create a well plan and drill
a well, according to a preferred embodiment of the invention;
[0024] FIG. 6 shows a portion of an interactive stability display
according to another embodiment of the invention; and
[0025] FIG. 7 is a flow chart showing steps of making a completion
plan and perforating a well according to an embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION:
[0026] According to a preferred embodiment of the invention, an
interactive display is provided that displays the predicted failure
state of the rock around the wellbore directly and graphically,
using a 3-dimensional display with a "click and drag" interface to
change the well orientation, and simple methods to choose earth and
drilling parameters. The display can be used to convey, quickly and
convincingly, the differences between drilling in different
directions or at different deviations, and the effects of changes
in mud weight, in-situ stress and rock properties. It can also be
used as an interpretation tool for comparing predicted deformation
patterns against well data, for example to establish bounds on the
stress state. According to one embodiment the display is used as a
fully-functional instability predictor by a oilfield service
engineer who is planning wells for a client. According to this
embodiment, any of the parameters can be changed by the user.
[0027] According to another embodiment, the display is used by an
oilfield asset owner or operator. According to this embodiment
either some or all of earth and rock parameters are hardwired in,
and the user is only allowed to change well orientation, mud weight
and a limited number of other parameters. For example, the users
could view a 3-D display on their own computer, examining the
effects of changes in well orientation, but not being able to alter
the stress state.
[0028] The wellbore instability predictions that are displayed
according to the invention are preferably based on calculations of
the stress state around the wellbore, and of the response of the
rock to these stresses. Even more preferably, the predictions are
based on an elastic model of rock behavior, which are known to be
conservative but having a clear advantages in terms of speed,
intelligibility, and amount of rock data required. Examples of
these types of calculations that can be used form the basis of
codes used by Schlumberger such those known as Roxan.TM.,
RockSolid.RTM., and IMPACT.RTM.. See also, Peska and Zoback, J.
Geophys. Research, 100, 1995 12791-12811; and Fjaer et al,
Petroleum Related Rock Mechanics, Elsevier, 1992, Chapter 4.
Alternatively various other mechanical models can be used, with
some being more complex models of rock behavior, for example by
incorporating plasticity. In accordance with the invention, an
elastic model is preferred because calculations of plasticity
around the wellbore can be time-consuming. However, under some
circumstances where response time is less important or a high
degree of processing power is available, a more complex model such
as one incorporating plasticity could be used. According to the
invention a relatively fast response time is an important feature
of the interactive display so that the results of the instability
calculations can be viewed by the user as the wellbore is moved
around. The fast response time advantageously increases the
usability and appeal of the display among a wide range of
users.
[0029] FIG. 1 shows an interactive stability display according to a
preferred embodiment of the invention. Interactive stability
display 100 comprises a display screen 102, a processor 107, a
storage system 108, and user input devices including a keyboard 104
and pointing device 106. According to a preferred embodiment
Interactive display 100 is implemented on a personal computer, and
even more preferably on a laptop personal computer. The interactive
stability display 100 can be programmed in a language such as
Matlab.RTM., although it is preferably implemented directly in a
Language such as C++. The display screen 102 is a two-dimensional
personal computer display, and even more preferably a LCD laptop
screen. Display screen 102 may comprise a number of windows or
other information associated with other applications or processes
running on the personal computer. Providing interactive display 100
on a laptop computer greatly enhances the wide range of working
environments for the user. Keyboard 104 is preferably a laptop
keyboard. Pointing device 106 is preferably a mouse, track pad,
trackball, joystick, but could alternatively be any other pointing
devices useable with a personal computer.
[0030] FIG. 2 shows features of the display screen, according to a
preferred embodiment of the invention. One of the main windows
displayed on display screen 102 is graphics window 110. Graphics
window 110 comprises primarily a three dimensional (3-D) display
112 and parameter information 114. As used herein the phrases
"three-dimensional display", "three-dimensional representation" and
"3-D display" include true three-dimensional display techniques
(e.g. volumetric and holographic displays), stereoscopic
three-dimensional display, and two-dimensional representations of
three-dimensional (e.g. perspective projection and parallel
projection). According to a preferred embodiment, 3-D display 112
is a parallel projection display. This has the advantage of not
requiring high levels of processing power or special hardware
beyond an ordinary monitor for a personal computer. The 3-D display
112 displays to the user a three-dimensional representation of
stability information of rock surrounding a wellbore. The 3-D
display 112 preferably shows: a bounding box 116 to aid in 3-D
orientation; a North/East/down coordinate system shown by broken
lines 120; the orientations and relative magnitudes of the
principal stresses indicated with axes 128; a hemispherical grid
118 to guide the user in orienting the portion of the wellbore; and
a portion of the wellbore itself 124, whose orientation can be
changed with the pointing device 106 using the small ball 122
(preferably brightly colored) as a handle. The portion of the
wellbore displayed is preferably relatively short such that the
parameters including rock properties, orientation and mud weight,
do not vary over the length of the portion. This allows for rapid
recalculation of the predicted stability information. For example,
it has been found that portions of 1 meter are suitable. In general
the suitable length depends in part on the variability of the
particular rock surrounding the wellbore. However, if sufficient
computational speed is available, the portion of the wellbore used
could be longer, up to the entire length of the well. It is also
preferable that the aspect ratio of the width and length of the
displayed portion of the wellbore is maintained to improve
usability. In practice, portions of less than 5 meters are
preferred if the displayed aspect ratio is to be maintained.
[0031] Buttons 134 are used for rotating the axes to manipulate the
viewing angle. It will be appreciated that buttons 134 can also be
used to display a plan view to the user. 3-D display 112
importantly displays a prediction of the stability (or instability)
state of the rock surrounding the portion of the wellbore 124. This
information is preferably displayed using an outline surface around
the portion of the wellbore, where the color of different parts of
the surface indicates the predicted stability of the corresponding
surrounding rock. For example, in FIG. 2 the shaded part of the
outline surface 126 is preferably displayed in a red color and the
unshaded portion is displayed in blue color. In the example of FIG.
2, the red shaded part 126 indicates clearly to the user that rock
failure is predicted in those portions of the rock surrounding the
portion of the wellbore.
[0032] The parameter information portion 114 of the display
comprises a number of boxes for entering and displaying various
parameters relating to the stability of the rock surrounding the
portion of the wellbore preferably including: stress magnitudes and
orientations, rock strength parameters, and the true vertical
depth. The true vertical depth is preferably used only to convert
fluid density (e.g. mud weight) to fluid pressure (e.g. mud
pressure). Parameter information portion 114 also includes boxes
that can be used to display and change wellbore azimuth and
deviation, and mud weight. However, according to a preferred
embodiment, these parameters are more easily changed using the
three-dimensional display 112 and a mud weight slider 136
respectively, and the boxes 130 display the values of the
parameters. Although the parameter information portion 114 is shown
to display certain preferred parameters, according to other
embodiments other parameters could also be displayed and/or
manipulated by the user, such as rock plasticity parameters, fluid
flow rates, temperatures, chemical and electrochemical properties,
and time since drilling.
[0033] According to a preferred embodiment, the instability
predictions displayed in 3-D display 112 are based on inputs
including: the magnitudes of the three principal stresses in the
earth at the depth of interest; their orientation relative to
North; the pore pressure; the rock strength, friction angle and
Poisson's ratio; the azimuth and deviation of the well; and the
fluid pressure (e.g. mud pressure) in the wellbore. These are used
to rotate the in-situ stress field into the wellbore coordinate
system; then to calculate the stress concentration around the
portion of the wellbore preferably using an elastic model; then to
compare the maximum and minimum local principal stresses to an
appropriate failure criterion (for example, the Mohr-Coulomb
criterion). The result is a function representing the extent by
which the local stress state exceeds the strength of the rock; in
simple terms whether the rock has failed and by how much. This
function is evaluated at a number of points around the portion of
the wellbore circumference and displayed in real-time to the user
via colored shading such as shaded part 126 around portion of the
wellbore 124 in 3-D display 112.
[0034] Whenever a parameter is charged, or the portion of the
wellbore orientation is changed, the equations for the stress state
and failure conditions around the wellbore are re-calculated, and
the color shading 126 of the portion of the wellbore 124 is
re-mapped to the value of the failure function. Although any
coloring scheme could be used, the invention preferably makes use
of colors that are quickly and clearly distinguishable by the user.
According to a preferred coloring scheme, the color of the surface
around the wellbore changes from blue through mauve to red as the
failure function moves from negative or zero (no failure under the
local stress state) through small positive values (mild rock
failure) to large positive values (severe rock failure). Because
the calculations are preferably carried out using an elastic model,
they are very quick, and so the wellbore color map, indicating the
failure state, is updated as the portion of the wellbore is moved
with the mouse, giving a high degree of interactivity with the
user.
[0035] According to another embodiment, the shape of the surface
surrounding the wellbore is distorted such that the cross section
of the surface is no longer round, in order to display to the user
an indication of the severity of the rock failure. As with the
simple color shading approach, this is very rapid and changes as
the wellbore is moved. The shape distortion can be used alone or
preferably in combination with the color shading approach.
[0036] Since the display shows both the extent of the potential
damage to the wellbore, and its location, it can be used both as a
tool to examine and demonstrate the effects of drilling at
different orientations and with different mud weights, and also to
interpret image logs that show wellbore damage, such as resistivity
at the bit (RAB) logs. Interpretation of the position of the damage
can help clarify the orientations and magnitudes of the principal
stresses in the earth.
[0037] FIG. 3 is a flow chart showing some processing steps
according to the invention as implemented on a computer. In step
210 the program is initialized and a set of default parameters are
read from memory. These default parameters could be originally
obtained from an earth model, or may be setup for the particular
region which the invention is intended to be used. In step 212 the
stability of the rock surrounding the wellbore is predicted based
on the current parameters. Following the initialization step 210,
the stability calculations in step 212 would be based on the
default parameters.
[0038] In step 214 the predicted stability of the rock surrounding
the wellbore is displayed to the user using a 3-D display,
preferably as described above with respect to FIG. 2. As discussed
above, the calculations underlying the predicted stability are
performed and the predicted stability is displayed in real time in
order to give the display a high degree of interactivity. In
particular the delay time for recalculation (and preferably
re-display) in real time based on a change in the orientation of
the portion of the wellbore by the user is preferably less than 2
seconds, and even more preferably is less than 0.2 seconds.
[0039] In step 216 a determination is made as to whether the
parameters being used give a suitable result in terms of stability
of the rock surrounding the portion of the wellbore. This
determination is preferably made by the user based on the viewing
the stability information being displayed on the 3-D display and
the current parameters. If the current parameters are not suitable,
the user indicates this by entering in new parameters, step 220, by
moving the pointing device to change the orientation of the well or
mud weight, and/or changing the parameter values in the data entry
boxes. If the user determines that the current parameters are
suitable, in step 218 the user proceeds with the remainder of the
drilling process. The user preferably indicates the parameter
acceptability to the computer program which then records and saves
the current parameters for future use. Alternatively, the user can
record the suitable parameters manually or electronically elsewhere
on the computer. In practice, the user is often interested most in
the mud weight and trajectory of the wellbore, given the parameters
set by the drilling environment.
[0040] FIG. 4 is a flow chart showing steps of planning and
drilling a well according to certain embodiments of the invention.
In step 310 at least some of the parameters used by the interactive
display are loaded from an existing earth model. In step 312 the
user uses the interactive display. In this case, the parameters
from the earth model are used as some or all of the initial
parameters in step 210 of FIG. 3. In step 314 the selected or
preferred parameters, typically the orientation and/or mud weight
are obtained from the interactive display. In step 318 the
preferred orientation and/or mud weight are used to construct or
modify a well plan. For example, in light of the preferred
orientations obtained in step 314, the planned trajectory is
modified to incorporate one or more of the preferred orientations,
or incorporate orientations approximating one or more of the
preferred orientations, into an existing well plan. Finally, in
step 320 a well is drilled using the constructed or modified well
plan.
[0041] According to another embodiment of the invention, the
interactive stability display is used during a drilling operation.
During drilling, in step 322 the known orientation and a measured
fluid pressure (mud pressure in this case) are entered as
parameters in the interactive display. Other parameters may be used
from an earth model (step 310). In step 312 the user uses the
interactive display. In step 324, the rock failure predictions from
the interactive display are compared to information acquired from
RAB logs or other imaging tools taken from the well during the
drilling process. If an inconsistency is identified between the
measured and predicted information, either the earth model can be
updated, the well plan can be modified (e.g. with a new trajectory
and/or mud weight), or both. In step 328, the remainder of the well
is drilled using the modified well plan.
[0042] According to another embodiment the interactive display can
be used to predict rock stability in an open hole during
production. According to this embodiment, in step 322 the known
orientation for a portion of the open hole wellbore and the
measured fluid pressure (in this case the pressure of the
production fluid) is entered into the interactive display along
with data from an earth model. In step 312 the interactive display
is used. In step 330 rock stability predictions are obtained for
the open hole wellbore. In light of the stability predictions a
preferred or selected drawdown pressure is obtained, and in step
332, the production is carried out using the preferred drawdown
pressure.
[0043] Alternatively, according to another embodiment, in step 334,
the interactive stability display can be used to diagnose a problem
encountered during drilling or during production. For example, if a
rock failure is suspected in an open hole section of the wellbore
during production, the interactive stability display can be used to
aid in evaluating the likely location of the failure (in terms of
both depth and circumferential position) and consequences (e.g.
crushing of a screen, or disruption of gravel pack).
[0044] FIG. 5 is a diagram showing the implementation of an
interactive stability display used to create a well plan and drill
a well, according to a preferred embodiment of the invention.
According to this embodiment, interactive stability display 100 is
running on a laptop PC. The interactive stability display 100
obtains at least some of the parameters used in predicting the
stability of the rock surrounding the wellbore from an earth model
stored on storage system 412 of computer system 410. Computer
system 410 can be directly connected to the laptop PC via a network
connection or dial-up connection, or it could be connected via a
wireless connection. Furthermore, the connection between computer
system 410 and the laptop PC can be permanent but is preferably
temporarily established to load initial parameters and settings and
to record and store output parameters such as orientation and/or
mud weight. In some cases some data in the earth model can be
updated in light of the results from the interactive stability
display 100.
[0045] The selected orientation and or mud weight is then used to
construct or modify a well plan, as described above. The well plan
may be on a separate computer 420 as shown in FIG. 5, the same
laptop PC as display 100, or it may be produced and used in
hard-copy form. According to the invention, the well plan on
computer 420 is then used to drill a well 424.
[0046] FIG. 6 shows a portion of an interactive stability display
according to another embodiment of the invention. In particular the
window 510 is preferably used when planning the location and
arrangement, or phasing, of perforations made during well
completion in order to establish fluid communication between the
surrounding reservoir rock and a conduit within the wellbore used
to produced fluids. Many of the features of window 510 are as
described with respect to FIG. 2 above. According to a preferred
embodiment, the outer surface of the portion of the wellbore 124 is
not shaded, but rather the perforations 520 are each shaded with
colors according to the predicted stability of the rock surrounding
the perforation. The surface of the wellbore 124 does not
ordinarily need any color shading since the wellbore is normally
cased at the time the perforations are shot.
[0047] The perforations 520 can also be arranged and relocated with
respect to the portion of the wellbore preferably by clicking on
the perforation and dragging the perforation to a new location. The
user can also add new perforations through a menu or similar means.
Other techniques could be used to add, delete, and move the
location of perforations including: menus, radio buttons and the
like. Another option for changing the arrangement of the
perforations that is provided is for the user to rotate some or all
of the perforations about the central axis of the portion of the
wellbore.
[0048] According to the preferred embodiment, the perforations are
always positioned perpendicular to the central axis of the portion
of the wellbore because this is how most if not all perforations
are commercially made. However, according to another embodiment of
the invention the interactive display could allow for the changing
of the inclination angle and orientation of a perforation relative
to the central axis of the portion of the wellbore, which is
initially set at 90 degrees. According to another embodiment, the
length of a perforation can be changed from an initial value by
right clicking on the perforation and entering a value in a pop up
menu. According to another embodiment, a perforation can be
selected by right clicking and then from a menu the user can choose
to have a detailed view of the perforation in a format similar to
that shown by the portion of the wellbore 124 and shaded area 126
in FIG. 2, except that the surface and shading represents the
stability of the selected perforation instead of a wellbore.
[0049] FIG. 7 is a flow chart showing steps of making a completion
plan and perforating a well according to an embodiment of the
invention. In step 330 at least some of the parameters used by the
interactive display for planning perforations are loaded from an
existing earth model. In step 332 the interactive display for
planning perforations is used by the user. In step 334 the selected
or preferred parameters, typically the preferred location and
direction for the perforations are obtained from the interactive
display. In step 338 the preferred location and direction of the
perforations are used to construct or modify a completion plan.
Finally, in step 340 a well is perforated using the completion
plan. It will be appreciated that the implementation shown in FIG.
5 and described above can be used with the embodiments for planning
perforations for a well.
[0050] While the invention has been described in conjunction with
the exemplary embodiments described above, many equivalent
modifications and variations will be apparent to those skilled in
the art when given this disclosure. Accordingly, the exemplary
embodiments of the invention set forth above are considered to be
illustrative and not limiting. Various changes to the described
embodiments may be made without departing from the spirit and scope
of the invention.
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